Final answer:
Syrup is the most viscous liquid among the options given, which also include water, lemonade, and soda, due to its high resistance to flow.
Step-by-step explanation:
The question asks which of the following liquids is the most viscous: A. Syrup, B. Water, C. Lemonade, D. Soda. Viscosity is a measure of a liquid's resistance to flow. Liquids like water, gasoline, and lemonade, which flow freely, have a low viscosity while others like syrup and motor oil flow more slowly, indicating high viscosity. Based on the given information, syrup is the correct answer, as it flows more slowly and is resistant to flow due to its high viscosity. Tests for viscosity include measuring the rate a metal ball falls through the liquid, with it falling more slowly through more viscous substances, or measuring how quickly the liquid flows through a narrow tube, where more viscous liquids flow slowly.